Rotor pump seal



Fel). 231965 v 5 B MGLEOD ETAL 3,170,409

ROTOR PUMP SEAL Filed April 1, 1963 INVENTORS Mll/m ATTORNEY United safes Faremo 3,170,409` ROTOR PUMP SEAL Stewart B, McLeod, Southfield, andV RobertE. Sdielhart, Dearborn, Mich., assignors toDura Corporation, Oak

Park, Mich.,.a corporationof Michigan Filed Apr. 1, 1963, Se'r. No; 269,473v 8 Claims. (Cl. 10S- 126) This invention relates totluid transfer pumps in general and more particularly to rotary pumps and the uid sealing problems thereof.

Rotary pumps require that the parts thereof be kma-V I'chinedto much closer tolerances-thanother type pumps. This applies to the uid pumping faces ofthe pump parts ybut equally as well to the end-tofenddimensions of rotor parts and bores to precludefliuidvolume and pressure losses either betweeny or around the fluidl trari'sferparts. Providing, an edequate illuid sealbetween relatively rotatably parts is always a problem but itis particularly'diiiicult where .several relatively rotatable parts are 'involved and sniall'size pump parts are desirable.

A Gerotor type pump such as is used in a pump, `'motor and iluidreservoiriassembly to supply hydraulic lfluid topower cylindersv of a'convertible folding top "mechanism provides a good example -fo'r explaining the "scope of the problem mentioned and the `solution to'such problems oflere'd by this invention. In a Gerotor type pump there are cooperative `and rel- 'atively rotatable internal and external yrotor parts which 'are received'within a rotor chamber or boreina housing para The rotor 'chamber or bore is closed at one end by a.cover, or a housing part `which vserves such pur- '1pose, and theA internal rotor is driven bya shaft extended through the other end of' the 'housing and engaged therewith; The internalrotor'drives the external rotor 'and bothrotate relatively and withrespecttor the end.

walls-of the rotor chamber; I Y

'l In this typepuirrprtheV inlet and outletports are' formed 'through one of the rotorV chamber end wallsand'- are provided in open communication between the relatively 'rotatably rotor parts and ondiamet'rically opposite sides thereof; Accordingly, any undue clearancebetween the 'ends of the' rotor parts and the `wall closing the rotor "chamber provides a directfpassageway between'the'iiid 'inlet and outletports.

" A pump having a `oneiinch rotor will require vtolerances 'as-close as .0005 in the depth of the rotor chamberbo're 'and .0003 thickness for the rotor parts. This usually 'means problems in matching rotor parts to each other 'as well as to particular housing bores, if losses are to be minimized, and requires further expense inthis regardi Just as close tolerances must be maintained to prevent fluid volume and pressure losses across the purnp,rit`

is also obviousthat reasonablegclearance or other means lmust be provided to enable free movement vof the rotor Vparts Without binding, scoringpressures or the like which might later cause pump failuresfor ineiciencies:

Patented'Feb. 23, 1965` rne'rousY problems` in' small pump assemblies. They.' nor` mally include a'discand a small spring vor a springwiasher` which makes assembly extremely difficult. AThe `1s`pring or spring washer is" receivedf between the rotorVV chamber'` cover andtheI sealing disc. Thespring pressure must" be light to prevent binding andrthere is invariably af wear; problemsooner or late'r;

Itis vanY object of this invention to'provide a fluid# pressure seal for rotary pumps and others which is'simple y plementgthetoreeof magnetic attractionfand to-keep` the seal seated landprevent uid passagebetween'rinlet l The `tlux attachmentl between` the K magnetic disc and rotor" parts providesI no hindrance and outlet parts.

to'relative movement between'the rotor-parts, and the resultant eciency of the fluid pumps is imrneasurably` Y improved.

TheseY and other objects 1 and advantages tov bey gained in practice of-A this invention will be better? understoodI Y and appreciateduponrareading of the-followingspecil cationin regard' to a preferred embodimen-t of the 1ini vention and having reference to theaccompanying-draw ings wherein:

FIGURE `1 is a side Viewy of 4a* pump, motor-v Vmidi reservoirassembly' havingl parts broken' away andrshowu'V in cross-section to better show an embodiment of this invention-used therein.' i

" In the past efforts have been vmade to provide Veither p' 'a iluid pressure seal or a spring loaded sealb'etween `the "rotor and cover members inr this type of pump'. How# ever, neither have provenk acceptablel and thef close tolerance requirements have prevailed; n l Fluid pressure seals normally include a small ldisc re- "ceived between the cover and rotor parts with meansr lfor applying the pump pressure between the disc and theil'cover to seat the seal on the rotor parts. The sealing vpressure must be light to avoid any, interference with the rotor drive and it :must be effected before uid passage `occurs under the seal. Otherwise the .seal is either 'seated against the cover or balanced up off Athe'rotor partsA and is ineffective. l Spring loaded seals`on` theothe'r' hnd"preserit`nu FIGURE 2 is an enlarged eross-sectional viewof-the pump portion of the assembly shown by FIGUREA 1` as seen in the plane'of line 22thereon. i

FIGURE 3 is an enlarged, fragmentary, and crosssectional vievvjofV the 'pump portion of the assembly' shownfby FIGUREVI, with-fthe detailsfo'f theiluid pres-Y 1 sure sealing means of thisfinvention shown` more clearly.;

FIGURE 4 is an exploded-view of certain'purp parts and the fluid seal of this `-in'ventio'n 4'as*takeir'fro'm FIG-v URE 3. n

' FIGURE '11 shows' an assembly 1o: ineiudin'g afmeren housing 12, pump :14 Vandre-Servon" member '16?.

provided in the 'ihousings shell 'i lS aiid'has the f slfft i -22 ment f with' the `operable parts thereof.

`The pump v14J includes at pump"A housing? ahdkover l Vparts24ai1d'26 respectively; 1`

Referring to FIGURE 3; the pump :housing l24 i" aicylindrical bore 28 provided in ani eneli f'ce' theief and receptive of the operable parts f of thefpiimpilter described; -A` passage' 30' is provided thrughf'thebth are provided thereinj,

Ihe cover part 2,6 of; piulipf1ffisk secured tov lthie'end of the housin-'g'part24fby'thieaded'b'oltfastener 39.;It Y includes a recess"40`form"ed in the face'tliereof abutting thev housing partand in concentric alignmentwiththe i bore 28 which, Vas Vpreviously mentioned, is receptive of' theope-rative partsiof the pump. The recess 40 is itself receptive of an annular disc 42 of magnetic material.

The reservoir member 16 includes a housing or shell 44 which is secured to the cover part 26 of the pump 14 by a'tie bolt 46. A fluid reservoir chamber space 48 is providedwithin the housing or shell'44 and suitable reservoir passages 50 and -52 are formed through the cover and housing parts 24 and 26 of the pump 14 for communication with the inlet and outlet passages 36 and 38 ofthe pump. .i

The motor, pump and reservoir assembly unit is of the type used to supply hydraulic fluid to one or more hydraulic cylinders such as may be used to operate a folding convertible top vfor automotive vehicles. Accordingly, a reversible motor is used to operate the pump for supplying fluid from one or the other of the inlet andioutlet passages 36 and 38 through the pump and to the other thereof.

Although not specifically shown, it will also be appreciated that .the reservoir passages 50 and 52 include check valve 'means to assure communication only between the inlet side of the pump and the reservoir chamber inthe course of the fluid flow transfer. Such check valve means have not been specifically shown or described since they do not pertain to the present invitation other thanl as makes the overall fluid transfer system more efficient. f Y

Referring now to FIGURES 2-4:

Within the pump bore 28 is provided a wear place 54 and concentrically disposed internal and external rotor parts 56 and 58.

The .wear plate 54 is of plastic or like non-magnetic and wear resistant material. It is provided in the bottom of the rotor bore 28 and is formed to includeV crescent shaped inlet and outlet pasages 60 and'62 disposed on diametrically opposite sides thereof. Similarly -formed and disposed inlet and outlet ports 6 4 and 66 are provided through the pump housing' .part 24 and extend from the rotor chamber bore 28 to the inlet and outlet Ipassages 36- and 3S to provide means of fluid flow communication therebetween. The wear plate 54 includes a positioning detent 68 which serves to locate it within the rotor chamber bore with its inlet and outlet passages alinged with the fluid flow inlet and outlet ports.

Referring to FIGURE 2, it will be noted that the drive shaft 22 is received eccentrically within the rotor bore 28 and similarly through a shaft passage 70 in the wear plate. The end of the drive shaft V22 is in turn formed for drivingengagement with the internal rotor member 56 within' a D-drive slot `72 provided therein.

The internal or inner disposed rotor member 56 is formed to include teeth 74 formed for driving engagement with the outer disposed or external rotor part 58. The outer rotor part 58 is, in turnformed to include lobes 76 between which the inner rotor teeth 74 are engaged and overwhich the teeth pass in the transfer of fluid in the manner commonly known with such cooperative rotor parts. For purposes of discussion Vthe expanded and contracted fluid pockets formed between the rotor parts in the course of their relative rotation will henceforth be referred to as the pump chamber space and `is identified in the drawings by the numeral 78.

The magnetic discs 42 Ywhich is disposed within the cover recess 40 is annular in shape and with an exteral rotor member which is one inch in diameter and it is about one-eighth inch in thickness. The disc is disposed to overlap both of the rotor .parts and to close the ends of the chamber spaces provided therebetween. It is of less thickness than' the cover recess 40 and a clearance space 80 is accordinglyk present between the disc and the end wall 82 of the cover recess.

The housing part 24 and cover part 26 are of a nonmagnetic material, as a zinc or aluminum die casting, while vthe rotor vparts 56 and 58 are themselves magnetically responsive.

The Adisc 42 is accordingly magnetically attracted and normally retained to the rotor parts by magnetic flux lines passing therebetween.

In the operation of the disclosed motor, pump and reservoir assembly 10 the magnetic disc 42 provides a fluid seal in the manner hereinafter described:

When the drive motor is started, the drive shaft 22 turns the internal rotor member 56 in one direction or the other and it in turn drives the external rotor 58 and the transfer of fluid across the pump commences.

Fluid flow is induced through one of the inlet and outlet passages 36 and 38 to the appropriate supply port l64 or 66. The reservoir check valve system (not shown) opens the appropriate reservoir passage 50 or 52 and closes the other thereof. Fluid flow is accordingly obtained through the inlet port to the rotor bore 28 and within the appropriate pump chamber spaces between the rotor members 56 and 458 in the course of their rotation.

The initial build-up of fluid pressure within the inlet fluid passage will also cause fluid to bleed and pass under the rotor part 56, about the end of the drive shaft 22, through the D-drive slot 72 in the rotor part 56 centrally through the annular magnetic disc 42 and to the clearance space on the back side thereof and between the magnetic disc and the end wall 82 of the disc receptive recess 40 provided in the pump cover part 26.

The magnetic attraction of the annular disc 42 to lthe rotor parts assures an initial closure engagement over the chamber space between the rotor parts and also assures having the clearance space 80 over the disc.

The permissive bleeding or flow of fluid through the disc 42 to the clearance space 80 is provided to assure proper seating thereof, to supplement the force of magnetic -attraction holding the annular disc in sealing relation over the rotor parts, and also to provide a light pressure seal to safeguard against fluid pressure within the pump chamber spaces having an initial build-up.

sufficient to lift the magnetic disc from its magnetically attracted engagement with the rotor parts and permit a by-passing fluid 4flow across the ends of the rotor parts which is the very thing to be avoided. The fluid pressure within the clearance lspace 80 is suf'licient to counteract the fluid pressure within the pump chamber spaces 78 and to yassure magnetic attraction of the disc 42 to the rotor parts precluding this cross flow. Furthermore,

once this pressure build-up is obtained within the clearance space 80 the magnetic disc 42 itself, by the pressure applied on the opposite face of the internal rotor member 56 precludes any significant fluid flow to the clearance space or otherwise under the rotor parts and between the pump chamber spaces.

Neither the magnetic flux connection of the magnetic disc 42 to the rotor parts, nor the fluid pressure assuring such connection, interferes with the relative movement between the rotor parts. The flux lines of attraction are readily sheared and re-established at points of relative Contact between the magneticv disc and the respective rotor parts.

The relative movement between the disc and rotor parts is minimal since it is only such as exists between the rotor parts themselves. That is, the magnetic disc 42 will rotate with one of the rotor parts and will move relative to the other thereofv only in the same respect as the rotor parts more relative to each other.

No wear will be experienced as regards the magnetic disc 42 and the end wall 82 of the cover recess 4) since the two are not in engagement and a fluid film is provided therebetween.

With the magnetic seal of this invention, supplemented by the pressure seal in the manner disclosed, fluid flow through the pump 14 is through one of inlet and outlet passages 36 and 38, to the pump chamber spaces between the rotor members S6 and 58 and through the other of the inlet and outlet passages without significant fluid vtail, it will be appreciated that this has been done to illustrate the scope of the present invention and without intent to unnecessarily limit the invention thereto in'V any regard. Accordingly, such improvements, modications and alterations as come `to mind and are within the spirit of this invention and are not specifically excluded by thelanguage of the hereinafter appended claims are to be considered as inclusive thereunder.

We claim:

1. In a rotor gear pump including a fluid receptive chamber and having a pair of relatively rotatable geartoothed fluid pumping rotor members provided Ain concentric and eccentric relation therein, With fluid transfer spaces provided therebetween in the course of'their rotation and open on one axial side of Vsaid chamber,

the method of sealing said pump against uid ow between said transfer spaces, comprising;

providing means in magnetically retained obstructing relation across the open ends of said transfer spaces.

2. The method of sealing a rotor gear `pump of claim 1, and including;

magnetically attracting said means to yat least one of said rotors for rotation therewith and from engagement withthe end wall of said chamber.

3. The sealing method for rotor gear pumps of claim 2, including;

biasing said magnetically attracted means for engagement with said rotors just prior to and in the course of iluid transfer through said pump.

4. In a rotor gearpump including a uid receptive chamber and having a pair of relatively rotatable geartoothed fluid pumping rotor members provided in concentric and eccentric relation therein,'with fluid transfer spaces provided therebetween in the course of their rotation and open onone axial side of said chamber,

sealing means, comprising;

an axially moveable disc provided on the side of said chamber on which said uid transfer spaces are open,

and means magnetically attracting said disc to said rotors for rotation therewith and the closing of the spaces formed therebetween.

5. In the rotor gear pump of claim 4,

said disc being magnetic for attraction to said rotors and said chamber having a non-magnetic end wall pn the opposite side of said disc from said rotors,

6. In a rotor gear pump including a` iiuid receptive chamberand having a pair of relatively rotatable geartoothed uild pumping rotor members provided in concentric and eccentric relation therein, with iiuid transfer spaces provided therebetween in the course of their rotationV and open on one axial side of said chamber,

, sealingmeans, comprising;

-an axially magnetic disc of a thickness receptive between the ends of said rotors and the end wall of said chamber next thereof for magnetically retained engagement with the former closing said iiuid transfer spaces and spaced disposition apart from said chamber end wall. p Y

7. In a rotor gear pump including a fluid receptive chamber and havinga vpair .of'relatively rotatable geartoothed uid pumping rotor members provided in concentric and eccentric relation the-rein, with'fluid transfer spaces provided therebetween in the course of 'their rotation and open on one axial side of said chamber,`

transfer spacesv and across the ends of said rotors, comprising; v

a chamber closing cover having a chamber joining clearance space provided therein,

an axially moveable disc provided in said clearance space,

said disc being magnetic and said chamber closing cover lbeing non-magnetic.

and said rotor members being of a material attractive of said disc in overlapping end engagement therewith and therebetween for closing said transfer spaces. l

8. In the rotor gear pump of claim 7;

fluid passage means provided through said disc to Ithe back side thereof for uid pressure supplementation of the attractive force holding said disc in engage ment with said rotor parts.

References Cited in the ile of this patent UNITED STATES PATENTS means for preventing the now of fluid between saidl 

4. IN A ROTOR GEAR PUMP INCLUDING A FLUID RECEPTIVE CHAMBER AND HAVING A PAIR OF RELATIVELY ROTATABLE GEARTOOTHED FLUID PUMPING ROTOR MEMBERS PROVIDED IN CONCENTRIC AND ECCENTRIC RELATION THEREIN, WITH FLUID TRANSFER SPACES PROVIDED THEREBETWEEN INTHE COURSE OF THEIR ROTATION AND OPEN ON ONE AXIAL SIDE OF SAID CHAMBER, SEALING MEANS, COMPRISING; AN AXIALLY MOVEABLE DISC PROVIDED ON THE SIDE OF SAID CHAMBER ON WHICH SAID FLUID TRANSFER SPACES ARE OPEN, AND MEANS MAGNETICALLY ATTRACTING SAID DISC TO SAID ROTORS FOR ROTATION THEREWITH AND THE CLOSING OF THE SPACES FORMED THEREBETWEEN. 